The present disclosure relates to an internal combustion engine and a method for manufacturing an internal combustion engine.
Japanese Laid-Open Patent Publication No. 2010-174734 discloses an internal combustion engine. A cylinder block of the internal combustion engine includes a blow-by gas passage that returns blow-by gas leaked into an oil pan to an intake passage. The upstream end of the blow-by gas passage opens toward an inner side of the oil pan, and the downstream end of the blow-by gas passage opens in an outer surface of the cylinder block. An oil separator is connected to the downstream opening of the blow-by gas passage. The oil separator is connected to the intake passage of the internal combustion engine through a recirculation passage.
With the internal combustion engine described in the publication, volatile fuel flowing into the oil separator along with the blow-by gas is liquefied in the oil separator. A portion of the liquefied oil flows downward into the oil pan through the blow-by gas passage. In this case, if the blow-by gas rushes into the blow-by gas passage from the oil pan, the flow of the blow-by gas may force the oil back to the oil separator.